Elements of Episodic Memory is a classic text in the psychology literature. It had a significant influence on research in the area has been much sought after in recent years. Finally, it has now been made available again with this reissue, the text unchanged from the original.

The paradigmatic assumption that REM sleep is the physiological equivalent of dreaming is in need of fundamental revision. A mounting body of evidence suggests that dreaming and REM sleep are dissociable states, and that dreaming is controlled by forebrain mechanisms. Recent neuropsychological, radiological, and pharmacological findings suggest that the cholinergic brain stem mechanisms that control the REM state can only generate the psychological phenomena of dreaming through the mediation of a second, probably dopaminergic, forebrain mechanism. The latter mechanism (and thus (...) dreaming itself) can also be activated by a variety of nonREM triggers. Dreaming can be manipulated by dopamine agonists and antagonists with no concomitant change in REM frequency, duration, and density. Dreaming can also be induced by focal forebrain stimulation and by complex partial (forebrain) seizures during nonREM sleep, when the involvement of brainstem REM mechanisms is precluded. Likewise, dreaming is obliterated by focal lesions along a specific (probably dopaminergic) forebrain pathway, and these lesions do not have any appreciable effects on REM frequency, duration, and density. These findings suggest that the forebrain mechanism in question is the final common path to dreaming and that the brainstem oscillator that controls the REM state is just one of the many arousal triggers that can activate this forebrain mechanism. The “REM-on” mechanism (like its various NREM equivalents) therefore stands outside the dream process itself, which is mediated by an independent, forebrain “dream-on” mechanism. Key Words: acetylcholine; brainstem; dopamine; dreaming; forebrain; NREM; REM; sleep. (shrink)

Sleep researchers in different disciplines disagree about how fully dreaming can be explained in terms of brain physiology. Debate has focused on whether REM sleep dreaming is qualitatively different from nonREM (NREM) sleep and waking. A review of psychophysiological studies shows clear quantitative differences between REM and NREM mentation and between REM and waking mentation. Recent neuroimaging and neurophysiological studies also differentiate REM, NREM, and waking in features with phenomenological implications. Both evidence and theory suggest that there are isomorphisms between (...) the phenomenology and the physiology of dreams. We present a three-dimensional model with specific examples from normally and abnormally changing conscious states. Key Words: consciousness; dreaming; neuroimaging; neuromodulation; NREM; phenomenology; qualia; REM; sleep. (shrink)

Sleep researchers in different disciplines disagree about how fully dreaming can be explained in terms of brain physiology. Debate has focused on whether REM sleep dreaming is qualitatively different from nonREM (NREM) sleep and waking. A review of psychophysiological studies shows clear quantitative differences between REM and NREM mentation and between REM and waking mentation. Recent neuroimaging and neurophysiological studies also differentiate REM, NREM, and waking in features with phenomenological implications. Both evidence and theory suggest that there are isomorphisms between (...) the phenomenology and the physiology of dreams. We present a three-dimensional model with specific examples from normally and abnormally changing conscious states. Key Words: consciousness; dreaming; neuroimaging; neuromodulation; NREM; phenomenology; qualia; REM; sleep. (shrink)

The content of dreams and changes to the self were investigated in students moving to University. In study 1, 20 participants completed dream diaries and memory tasks before and after they had left home and moved to university, and generated self images, “I am…” statements , reflective of their current self. Changes in “I ams” were observed, indicating a newly-formed ‘university’ self. These self, images and related autobiographical knowledge were found to be incorporated into recent dreams but not into dreams (...) from other periods. Study 2 replicated these findings in a different sample . We suggest that these data reflect a period of self-consolidation in which new experiences and self images are incorporated into autobiographical memory knowledge structures representing personal goals during sleep. (shrink)

Sleep enhances integration across multiple stimuli, abstraction of general rules, insight into hidden solutions and false memory formation. Newly learned information is better assimilated if compatible with an existing cognitive framework or schema. This article proposes a mechanism by which the reactivation of newly learned memories during sleep could actively underpin both schema formation and the addition of new knowledge to existing schemata. Under this model, the overlapping replay of related memories selectively strengthens shared elements. Repeated reactivation of memories in (...) different combinations progressively builds schematic representations of the relationships between stimuli. We argue that this selective strengthening forms the basis of cognitive abstraction, and explain how it facilitates insight and false memory formation. (shrink)

Even though various investigations found a preponderance of negative emotions in dreams, the conclusion that human dream life is, in general, negatively toned is limited by several methodological issues. The present study made use of three different approaches to measure dream emotions: dream intensity rated by the dreamer, intensity rated by a judge, and scoring of explicitly mentioned emotions (Hall & Van de Castle, 1966). Results indicate that only in the case of external raters' estimates do negative emotions outweigh the (...) positive ones; but in the case of self-ratings (i.e., those made by the dreamer himself/herself), the ratio was balanced. Analyses showed that this is mainly due to the underestimation of positive emotions in the external ratings. Additionally, a positive correlation was found between the intensity of dream emotions and dream recall frequency, whereas gender differences were nonsignificant as regards the emotional tone of diary dreams. (shrink)

Binding can be described at three different levels: In neuroscience it refers to the integration of single-cell activities to form functional neural assemblies, especially in response to global stimulus properties; in cognitive science it refers to the integration of distributed modular input processing to form unified representations for memory and action, and in consciousness studies it refers to the unity of phenomenal consciousness . To describe and explain the unity of consciousness, detailed phenomenological descriptions of binding at the phenomenal level (...) and clarification of the underlying cognitive and neural mechanisms are required. The disunity of consciousness during dreaming is a fruitful avenue to study phenomenal binding and its mechanisms. The notion of the 'bizarreness' of dreams is closely related to the concept of 'binding': bizarreness can be reconceptualized as referring to different types of unusual combinations of features in the binding of dream images coherently together. The present study concentrates on the representation of human characters and the bizarreness found in these representations. We developed a rating scale that distinguishes different types of bizarreness on the basis of the unusual combinations of elements that are manifested in dream images. The data consisted of 592 dream reports in the home-based dream diaries of 52 students. The results indicate that about half of the human characters appearing in our dreams contain bizarre elements, and that certain types of bizarreness are more frequent than others. Phenomenal features intrinsic to the representation of a person are less frequently bizarre than is the external relation between the person and the context . Thus, binding the local features of a representation coherently together appears to be less prone to errors than binding several different information streams together into a coherent phenomenal model of the world. (shrink)

The dream-lag effect refers to there being, after the frequent incorporation of memory elements from the previous day into dreams, a lower incorporation of memory elements from 2 to 4 days before the dream, but then an increased incorporation of memory elements from 5 to 7 days before the dream. Participants kept a daily diary and a dream diary for 14 days and then rated the level of matching between every dream report and every daily diary record. Baseline matching was (...) assessed by comparing all dream reports to all diary records for days that occurred after the dream. A significant dream-lag effect for the 5–7 day period, compared to baseline and compared to the 2–4 day period, was found. This may indicate a memory processing function for sleep, which the dream content may reflect. Participants’ and three independent judges’ mean ratings also confirmed a significant day-residue effect. (shrink)

Thirty-eight “practiced” dreamers and 50 “novice” dreamers completed questionnaires assessing the cognitive, metacognitive, and emotional qualities of recent waking and dreaming experiences. The present findings suggest that dreaming cognition is more similar to waking cognition than previously assumed and that the differences between dreaming and waking cognition are more quantitative than qualitative. Results from the two studies were generally consistent, indicating that high-order cognition during dreaming is not restricted to individuals practiced in dream recall or self-observation. None of the measured (...) features was absent or infrequent in reports of either dreaming or waking experiences. Recollections of dreaming and waking experiences were similar for some cognitive features and different for other features. (shrink)

The dream-lag effect refers to there being, after the frequent incorporation of memory elements from the previous day into dreams , a lower incorporation of memory elements from 2 to 4 days before the dream, but then an increased incorporation of memory elements from 5 to 7 days before the dream. Participants kept a daily diary and a dream diary for 14 days and then rated the level of matching between every dream report and every daily diary record. Baseline matching (...) was assessed by comparing all dream reports to all diary records for days that occurred after the dream. A significant dream-lag effect for the 5–7 day period, compared to baseline and compared to the 2–4 day period, was found. This may indicate a memory processing function for sleep, which the dream content may reflect. Participants’ and three independent judges’ mean ratings also confirmed a significant day-residue effect. (shrink)

Dream is a state of consciousness characterized by internally-generated sensory, cognitive and emotional experiences occurring during sleep. Dream reports tend to be particularly abundant, with complex, emotional, and perceptually vivid experiences after awakenings from rapid eye movement sleep. This is why our current knowledge of the cerebral correlates of dreaming, mainly derives from studies of REM sleep. Neuroimaging results show that REM sleep is characterized by a specific pattern of regional brain activity. We demonstrate that this heterogeneous distribution of brain (...) activity during sleep explains many typical features in dreams. Reciprocally, specific dream characteristics suggest the activation of selective brain regions during sleep. Such an integration of neuroimaging data of human sleep, mental imagery, and the content of dreams is critical for current models of dreaming; it also provides neurobiological support for an implication of sleep and dreaming in some important functions such as emotional regulation. (shrink)

This article argues that rapid eye movement (REM) dreaming is elaborative encoding for episodic memories. Elaborative encoding in REM can, at least partially, be understood through ancient art of memory (AAOM) principles: visualization, bizarre association, organization, narration, embodiment, and location. These principles render recent memories more distinctive through novel and meaningful association with emotionally salient, remote memories. The AAOM optimizes memory performance, suggesting that its principles may predict aspects of how episodic memory is configured in the brain. Integration and segregation (...) are fundamental organizing principles in the cerebral cortex. Episodic memory networks interconnect profusely within the cortex, creating omnidirectional “landmark” junctions. Memories may be integrated at junctions but segregated along connecting network paths that meet at junctions. Episodic junctions may be instantiated during non–rapid eye movement (NREM) sleep after hippocampal associational function during REM dreams. Hippocampal association involves relating, binding, and integrating episodic memories into a mnemonic compositional whole. This often bizarre, composite image has not been present to the senses; it is not “real” because it hyperassociates several memories. During REM sleep, on the phenomenological level, this composite image is experienced as a dream scene. A dream scene may be instantiated as omnidirectional neocortical junction and retained by the hippocampus as an index. On episodic memory retrieval, an external stimulus (or an internal representation) is matched by the hippocampus against its indices. One or more indices then reference the relevant neocortical junctions from which episodic memories can be retrieved. Episodic junctions reach a processing (rather than conscious) level during normal wake to enable retrieval. If this hypothesis is correct, the stuff of dreams is the stuff of memory. (shrink)

Empirical studies largely support the continuity hypothesis of dreaming. Despite of previous research efforts, the exact formulation of the continuity hypothesis remains vague. The present paper focuses on two aspects: the differential incorporation rate of different waking-life activities and the magnitude of which interindividual differences in waking-life activities are reflected in corresponding differences in dream content. Using a correlational design, a positive, non-zero correlation coefficient will support the continuity hypothesis. Although many researchers stress the importance of emotional involvement on the (...) incorporation rate of waking-life experiences into dreams, Hartmann formulated the hypothesis that highly focused cognitive processes such as reading, writing, etc. are rarely found in dreams due to the cholinergic activation of the brain during dreaming. The present findings based on dream diaries and the exact measurement of waking activities replicated two recent questionnaire studies. These findings indicate that it will be necessary to specify the continuity hypothesis more fully and include factors which modulate the incorporation rate of waking-life experiences into dreams. Whether the cholinergic state of the brain during REM sleep or other alterations of brain physiology are the underlying factors of the rare occurrence of highly focused cognitive processes in dreaming remains an open question. Although continuity between waking life and dreaming has been demonstrated, i.e., interindividual differences in the amount of time spent with specific waking-life activities are reflected in dream content, methodological issues have limited the capacity for detecting substantial relationships in all areas. Nevertheless, it might be concluded that the continuity hypothesis in its present general form is not valid and should be elaborated and tested in a more specific way. (shrink)

Relatively poor memory for dreams is important evidence for Hobson et al.'s model of conscious states. We describe the time-gap experience as evidence that everyday memory for waking states may not be as good as they assume. As well as being surprisingly sparse, everyday memories may themselves be systematically distorted in the same manner that Revonsuo attributes uniquely to dreams. [Hobson et al.; Revonsuo].